Threaded fastener

0001This application claims the benefit of U.S. provisional application 62/199,416, filed on Jul. 31, 2015.

BACKGROUND AND SUMMARY

0002The present invention relates generally to threaded fasteners of any size, and more particularly to vibration resistant threaded fasteners.

0003Threaded fasteners such as screws are used in many applications to connect one component or part to another. Many screws are installed through a portion of one component and threaded into a second component to clamp the components together. Many component shapes and configurations have been contemplated for retaining a threaded fastener, such as a blind or through hole formed in the component for engaging the threads of the fastener. The blind or through hole may be provided in an embossment or may be provided in the component material thickness. Often the blind or through hole is threaded to mate with the threaded fastener.

0004Many applications including automotive, electronic, and consumer products require threaded fasteners that maintain desired clamping forces through vibration and other in-use loads. A common problem with prior fasteners included loosening under vibration. Other prior fasteners stripped too easily during installation providing reduced clamping and premature assembly failure. Certain prior fasteners create excessive radial stress around the hole during installation, particularly in an embossment, that weakens the component and may cause premature assembly failure.

0005Fastener coatings have been developed to compensate for some of the failures of prior fasteners, such as thread-sealing adhesives, thread lubricants, anti-vibration coatings, and patches of nylon or similar materials. However, thread coatings require additional material cost and application cost, and are increasingly difficult to apply as fastener sizes become smaller. There remains a need for a threaded fastener that overcomes these and other disadvantages of the prior art.

0006We have found that new thread profiles that provide multi-point contact improve the vibration resistance of the threaded fastener, and thereby greatly reduce and may eliminate the need for fastener coatings, such as nylon patches.

0007Therefore, what is disclosed is a threaded fastener with improved vibration resistance. The threaded fastener includes a first end, a second end, and a threaded portion extending between the first end and the second end. The threaded fastener also has a longitudinal axis extending through the fastener from the first end to the second end, and a normal axis extending perpendicular to the longitudinal axis.

0008In various embodiments, the threaded faster has a threaded portion configured to engage two or three points of a mating thread, and the threaded portion has a thread defined by, in series, a crest portion oriented at an angle of 10° to 20° relative to the longitudinal axis, a leading flank oriented at an angle of 20° to 30° relative to the normal axis, a root portion oriented at an angle of 25° to 35° relative to the longitudinal axis, and a trailing flank oriented at angle of 15° to 25° relative to the normal axis.

0009In one embodiment, the threaded fastener has a threaded portion configured to engage three points of a mating thread, and the threaded portion has a thread defined by, in series, a crest portion oriented at an angle of −5° to 5° relative to the longitudinal axis, a leading flank oriented at an angle of 30° to 40° relative to the normal axis, a root portion oriented at an angle of 22° to 32° relative to the longitudinal axis, and a trailing flank oriented at angle of 17° to 27° relative to the normal axis. In other embodiments, the thread is defined by, in series, the crest portion oriented at an angle of approximately 0° relative to the longitudinal axis, the leading flank oriented at an angle of approximately 35° relative to the normal axis, the root portion oriented at an angle of approximately 27° relative to the longitudinal axis, and the trailing flank oriented at an angle of approximately 22° relative to the normal axis. In yet other embodiments, the crest portion, the leading flank, the root portion, and the trailing flank may be oriented at +/−1° or +/−2.5° from the angles previously noted.

0010In another embodiment, the threaded fastener has a threaded portion configured to engage two points of a mating thread, and the threaded portion has a thread defined by, in series, a crest portion oriented at an angle of 10° to 20° relative to the longitudinal axis, a leading flank oriented at an angle of 20° to 30° relative to the normal axis, a root portion oriented at an angle of 25° to 35° relative to the longitudinal axis, and a trailing flank oriented at an angle of 15° to 25° relative to the normal axis. In other embodiments, the thread is defined by, in series, the crest portion oriented at an angle of approximately 15° relative to the longitudinal axis, the leading flank oriented at an angle of approximately 25° relative to the normal axis, the root portion oriented at an angle of approximately 30° relative to the longitudinal axis, and the trailing flank oriented at angle of approximately 20° relative to the normal axis. In yet other embodiments, the crest portion, the leading flank, the root portion, and the trailing flank may be oriented at +/−1° or +/−2.5° from the angles previously noted.

0011In another embodiment, the threaded fastener has a threaded portion configured to engage two points of a mating thread, and the threaded portion has a thread defined by, in series, a crest portion oriented at an angle of −5° to 5° relative to the longitudinal axis, a leading flank oriented at an angle of 25° to 35° relative to the normal axis, a first root portion oriented at an angle of −5° to 5° relative to the longitudinal axis, a second root portion oriented at an angle of 35° to 45° relative to the longitudinal axis, and a trailing flank oriented at angle of 21° to 29° relative to the normal axis. In other embodiments, the thread is defined by, in series, the crest portion oriented at an angle of approximately 0° relative to the longitudinal axis, the leading flank oriented at an angle of approximately 30° relative to the normal axis, the first root portion oriented at an angle of approximately 0° relative to the longitudinal axis, the second root portion oriented at an angle of approximately 40° relative to the longitudinal axis, and the trailing flank oriented at angle of approximately 24° relative to the normal axis. In yet other embodiments, the crest portion, the leading flank, the root portion, and the trailing flank may be oriented at +/−1° or +/−2.5° from the angles previously noted.

0012In some embodiments, the second end of the threaded fastener is tapered. In an embodiment, the major diameter of the crest portion of the threaded portion tapers at approximately 30° over at least the last two revolutions of the threaded portion adjacent the second end.

0013The presently disclosed threaded fastener may be internally or externally threaded. In addition, the threaded fastener may include internal or external driver surfaces. In one embodiment the threaded fastener has a recess into a shank which defines internal drive surfaces. In yet other embodiments, the threaded fastener includes a radially extending surface with a plurality of serrations.

BRIEF DESCRIPTION OF THE DRAWINGS

0014Reference is made to the accompanying drawings in which particular embodiments are illustrated as described in more detail in the description below, in which:

0015<figref idref="DRAWINGS">FIG. 1</figref> is a perspective view a threaded fastener;

0016<figref idref="DRAWINGS">FIG. 2</figref> is a cross-section view of the threaded fastener of <figref idref="DRAWINGS">FIG. 1</figref>;

0017<figref idref="DRAWINGS">FIG. 3</figref> is a detail view of a threaded portion of a first embodiment of a threaded fastener;

0018<figref idref="DRAWINGS">FIG. 4</figref> is a detail view of the first embodiment of a threaded fastener engaged to a component;

0019<figref idref="DRAWINGS">FIG. 5</figref> is a detail view of a second embodiment of a threaded portion of a threaded fastener;

0020<figref idref="DRAWINGS">FIG. 6</figref> is a detail view of the second embodiment of a threaded fastener engaged to a component;

0021<figref idref="DRAWINGS">FIG. 7</figref> is a detail view of a third embodiment of a threaded portion of a threaded fastener;

0022<figref idref="DRAWINGS">FIG. 8</figref> is a detail view of the third embodiment of a threaded fastener engaged to a component;

0023<figref idref="DRAWINGS">FIG. 9</figref> is a detail view of a second end portion of the first embodiment of a threaded fastener;

0024<figref idref="DRAWINGS">FIG. 10</figref> is a detail view of a second end portion of the second embodiment of a threaded fastener;

0025<figref idref="DRAWINGS">FIG. 11</figref> is a detail view of a second end portion of the third embodiment of a threaded fastener;

0026<figref idref="DRAWINGS">FIG. 12</figref> is a graph of vibration test results for embodiments of the threaded fastener and comparative fastener samples;

0027<figref idref="DRAWINGS">FIG. 13</figref> is a chart of seating torque test results for embodiments of the threaded fastener and a comparative fastener sample;

0028<figref idref="DRAWINGS">FIG. 14</figref> is a chart of torque off test results for embodiments of the threaded fastener and a comparative fastener sample.

DETAILED DESCRIPTION

0029Referring now to <figref idref="DRAWINGS">FIGS. 1-11</figref>, embodiments of the presently disclosed threaded fastener are illustrated. As shown in <figref idref="DRAWINGS">FIG. 1</figref>, a threaded fastener <b>100</b> includes a threaded portion <b>108</b> extending from a first end <b>102</b> to a second end <b>104</b>. The second end <b>104</b> may alternatively be referred to as the lead end of the fastener based upon the driving direction D of the fastener. In one embodiment, the threaded fastener is a screw having a head <b>106</b>. The threaded portion <b>108</b> is defined by a helical thread extending around an elongated shank that extends from the head <b>106</b> to the second end <b>104</b>. As described further below, the thread is defined by at least a crest portion, a leading flank, a root portion, and a trailing flank. The configuration of the thread may be defined by reference to a longitudinal axis and/or a normal axis of the threaded fastener. The longitudinal axis extends through the fastener from the first end to the second end, whereas the normal axis extends perpendicular to the longitudinal axis.

0030Referring now to <figref idref="DRAWINGS">FIG. 2</figref>, a cross-section of the threaded fastener <b>100</b> is illustrated. As shown, the thread portion <b>108</b> extends along the elongated shank with the helical thread repeating in cross-section, with the adjacent threads axially separated by the distance of the pitch. In an embodiment, the head <b>106</b> of the fastener includes internal drive surfaces <b>110</b> configured to receive a driver for transmitting torque to the fastener. In other embodiments, the head may include external drive surfaces. In yet other embodiments, the threaded fastener may be a headless screw, in which the first end includes a recess into the shank and the recess in the shank includes drive surfaces.

0031The configuration of the thread may provide improved vibration resistance as compared to previously available fasteners, while also reducing or eliminating the need for patches or other anti-vibration measures. <figref idref="DRAWINGS">FIGS. 3-8</figref> illustrate embodiments of the thread identified by Detail A in <figref idref="DRAWINGS">FIG. 2</figref> that provide improved vibration resistance. <figref idref="DRAWINGS">FIGS. 9-11</figref> illustrate embodiments of the second end identified by Detail B. The thread configurations described below are described in the context of an externally threaded screw, such as illustrated in <figref idref="DRAWINGS">FIGS. 1-2</figref>. The presently disclosed threaded fastener, however, encompasses externally threaded fasteners (e.g. screws, bolts, etc.) as well as internally threaded fasteners (e.g. nuts), as well as fastening systems that mate internally and externally threaded fasteners, where one or both of the fasteners is configured in accordance with this disclosure. In one embodiment, one fastening component has a thread configured in accordance with this disclosure, and the mating fastening component has a 60° symmetric thread profile, such as those defined by relevant standards including ISO 68, ISO 261, ISO 262, and ASME/ANSI B1, which are incorporated herein by reference.

0032Referring now to <figref idref="DRAWINGS">FIGS. 3-8</figref>, the configuration of the thread is illustrated for embodiments of the threaded fastener. The thread includes a crest portion, a leading flank, a root portion, and a trailing flank. The crest portion defines the major diameter of the threaded portion, and is defined in profile by an angle between the crest portion and the longitudinal axis of the fastener, also referred to as a crest angle δ. The leading flank is angled towards the lead end and is defined in profile by an angle between the leading flank and the normal axis (i.e. a plane normal to the longitudinal axis of the fastener), also referred to as the lead angle α. The root portion defines the minor diameter of the threaded portion and is defined in profile by an angle between the root portion and the longitudinal axis of the fastener, also referred to as the root angle ρ. The trailing flank is angled towards the first end (e.g. head) of the fastener, and is defined in profile by an angle between the trailing flank and the normal axis (i.e. a plane normal to the longitudinal axis of the fastener), also referred to as the trail angle β.

0033Referring now to <figref idref="DRAWINGS">FIGS. 3-4</figref>, a thread <b>200</b> of a first embodiment of a threaded fastener is illustrated. The crest portion <b>202</b> oriented at a crest angle δ of approximately −5° to 5° relative to the longitudinal axis of the fastener. The crest angle δ may also be approximately 0°. The leading flank <b>204</b> is oriented at a lead angle α of approximately 25° to 45° relative to the normal axis of the fastener. The lead angle α may also range from 30° to 40°, 32° to 38°, 34° to 36°, or is approximately 35°. The root portion <b>206</b> is oriented at a root angle ρ of approximately 17° to 37° relative to the longitudinal axis of the fastener. The root angle ρ may also range from 20° to 34°, 22° to 32°, 24° to 30°, 26° to 28°, or is approximately 27°. The trailing flank <b>208</b> is oriented at trail angle β of approximately 12° to 32° relative to the normal axis. The trail angle β may also range from 14° to 30°, 16° to 28°, 18° to 26°, 20° to 24°, or is approximately 22°.

0034Referring to <figref idref="DRAWINGS">FIG. 4</figref>, the thread <b>200</b> provides three-point contact with a mating thread <b>210</b>, which improves the vibration resistance of the threaded fastener. For purposes of illustration, the mating thread <b>210</b> is illustrated by a symmetric thread having a crest portion <b>212</b>, a first flank <b>214</b>, a root portion <b>216</b>, and a second flank <b>218</b>. The first flank <b>214</b> and the second flank <b>218</b> are oriented at approximately 60° relative to the normal axis, while the crest portion <b>212</b> and root portion <b>216</b> are oriented at approximately 0° relative to the longitudinal axis. This configuration is common in commercially available screws and nuts.

0035When the thread <b>200</b> is mated with the mating thread <b>210</b>, the configuration of the thread <b>200</b> results in three points of contact as shown in <figref idref="DRAWINGS">FIG. 4</figref>. The leading flank <b>204</b> of the thread <b>200</b> contacts the crest portion <b>212</b> of the mating thread <b>210</b> at a first contact point <b>220</b>. The root portion <b>206</b> of the thread <b>200</b> contacts the crest portion <b>212</b> of the mating thread <b>210</b> at a second contact point <b>222</b>. The crest portion <b>202</b> of the thread <b>200</b> contacts the first flank <b>214</b> of the mating thread <b>210</b> at a third contact point <b>224</b>. As will be apparent, each of the contact points between the thread and the mating thread extend helically along the length of the threaded fastener further improving the stability and vibration resistance.

0036The multi-point contact between the thread <b>200</b> and the mating thread <b>210</b> improves the vibration resistance of the threaded fastener by limiting vibration induced movement. By locking the crest portion of the thread with the mating thread, and locking the root portion of the thread with the mating thread, the potential for movement as a result of vibration is significantly reduced. In contrast, a conventional thread having symmetric 60° leading and trailing flanks, contacts the mating thread only along the flanks leaving significant radial clearance at both the crest and root. That radial clearance permits vibration induced movement which results in loosening of the fastener as shown in the test results below.

0037Referring now to <figref idref="DRAWINGS">FIGS. 5-6</figref>, a thread <b>300</b> of a second embodiment of a threaded fastener is illustrated. The crest portion <b>302</b> oriented at a crest angle δ of approximately 5° to 25° relative to the longitudinal axis of the fastener. The crest angle δ may also range from 7° to 23°, 9° to 21°, 11° to 19°, 13° to 17°, or approximately 15°. The leading flank <b>304</b> is oriented at a lead angle α of approximately 15° to 35° relative to the normal axis of the fastener. The lead angle α may also range from 17° to 32°, 19° to 30°, 21° to 28°, 23° to 26°, or may be approximately 25°. The root portion <b>306</b> is oriented at a root angle ρ of approximately 20° to 40° relative to the longitudinal axis of the fastener. The root angle ρ may also range from 22° to 38°, 24° to 36°, 26° to 34°, 28° to 32°, or may be approximately 30°. The trailing flank <b>308</b> is oriented at trail angle β of approximately 10° to 30° relative to the normal axis. The trail angle β may also range from 12° to 28°, 14° to 26°, 16° to 24°, 18° to 22°, or may be approximately 20°.

0038Referring to <figref idref="DRAWINGS">FIG. 6</figref>, the thread <b>300</b> provides two-point contact with a mating thread <b>310</b>, which improves the vibration resistance of the threaded fastener. For purposes of illustration, the mating thread <b>310</b> is illustrated a symmetric thread having a crest portion <b>312</b>, a first flank <b>314</b>, a root portion <b>316</b>, and a second flank <b>318</b>. The first flank <b>314</b> and the second flank <b>318</b> are oriented at approximately 60° relative to the normal axis, while the crest portion <b>312</b> and root portion <b>316</b> are oriented at approximately 0° relative to the longitudinal axis. This configuration is common in commercially available screws and nuts.

0039When the thread <b>300</b> is mated with the mating thread <b>310</b>, the configuration of the thread <b>300</b> results in two points of contact as shown in <figref idref="DRAWINGS">FIG. 6</figref>. The root portion <b>306</b> of the thread <b>300</b> contacts the crest portion <b>312</b> of the mating thread <b>310</b> at a first contact point <b>320</b>. The crest portion <b>302</b> of the thread <b>300</b> contacts the first flank <b>314</b> of the mating thread <b>310</b> at a second contact point <b>322</b>.

0040As described above, the multi-point contact between the thread <b>300</b> and the mating thread <b>310</b> improves vibration resistance of the threaded fastener by limiting vibration induced movement. By locking both the crest portion and the root portion of the thread with the mating thread, the potential for movement as a result of vibration is significantly reduced as shown by the test results below.

0041Referring now to <figref idref="DRAWINGS">FIGS. 7-8</figref>, a thread <b>400</b> of a third embodiment of a threaded fastener is illustrated. The crest portion <b>402</b> oriented at a crest angle δ of approximately −5° to 5° relative to the longitudinal axis of the fastener. The crest angle δ may also be approximately 0°. The leading flank <b>404</b> is oriented at a lead angle α of approximately 20° to 40° relative to the normal axis of the fastener. The lead angle α may also range from 22° to 38°, 24° to 36°, 26° to 34°, 28° to 32°, or approximately 30°. The root portion of the thread <b>400</b> includes a first root portion <b>406</b> and a second root portion <b>407</b>. The first root portion <b>406</b> is oriented at a first root angle ρ₁of approximately 0° relative to the longitudinal axis of the fastener. The second root portion <b>407</b> is oriented at a second root angle ρ₂of approximately 30° to 50° relative to the longitudinal axis of the fastener. The second root angle ρ₂may also range from 32° to 48°, 34° to 46°, 36° to 44°, 38° to 42°, or approximately 40°. The trailing flank <b>408</b> is oriented at trail angle β of approximately 14° to 34° relative to the normal axis. The trail angle β may also range from 16° to 32°, 18° to 30°, 20° to 28°, 22° to 26°, or is approximately 24°.

0042Referring to <figref idref="DRAWINGS">FIG. 8</figref>, like the second embodiment previously discussed, the thread <b>400</b> provides two-point contact with a mating thread <b>410</b>, which improves the vibration resistance of the threaded fastener. For purposes of illustration, the mating thread <b>410</b> is illustrated a symmetric thread having a crest portion <b>412</b>, a first flank <b>414</b>, a root portion <b>416</b>, and a second flank <b>418</b>. The first flank <b>414</b> and the second flank <b>418</b> are oriented at approximately 60° relative to the normal axis, while the crest portion <b>412</b> and root portion <b>416</b> are oriented at approximately 0° relative to the longitudinal axis. This configuration is common in commercially available screws and nuts.

0043When the thread <b>400</b> is mated with the mating thread <b>410</b>, the configuration of the thread <b>400</b> results in two points of contact as shown in <figref idref="DRAWINGS">FIG. 8</figref>. The second root portion <b>407</b> of the thread <b>400</b> contacts the crest portion <b>412</b> of the mating thread <b>410</b> at a first contact point <b>420</b>. The crest portion <b>402</b> of the thread <b>400</b> contacts the first flank <b>414</b> of the mating thread <b>410</b> at a second contact point <b>422</b>.

0044As described above, the multi-point contact between the thread <b>400</b> and the mating thread <b>410</b> improves vibration resistance of the threaded fastener by limiting vibration induced movement. By locking both the crest portion and the root portion of the thread with the mating thread, the potential for movement as a result of vibration is significantly reduced as shown by the test results below.

0045Referring generally to <figref idref="DRAWINGS">FIGS. 3-8</figref>, the embodiments of the thread for the presently disclosed threaded fastener have been described by angle relative to the longitudinal axis or normal axis of the threaded fastener. The phrase “approximately X°” is intended to mean a design or specified value of X, while allowing for standard manufacturing tolerances and variations. In one example, manufacturing tolerances and variations may be up to and including +/−0.5°. In various embodiments, the angles defining each portion of the thread configuration may vary by +/−1°, +/−2.5°, +/−5°, while still achieving the improved vibration resistance. Moreover, the variation of angle need not be uniform across all portions of the thread configuration. For example, in one embodiment, the crest portion and root portion may vary by +/−5° from the angles illustrated above, while the leading flank and trailing flank are held within +/−1° of the angles illustrated above. All such variations are contemplated as within the scope of this disclosure. In addition, a range defined by “+/−” a certain value are intended to be inclusive of the end points of the range. For example, “0°+/−5°” means −5° to +5° inclusive.

0046Referring now to <figref idref="DRAWINGS">FIGS. 9-11</figref>, the second end portions of the embodiments of the threaded fasteners illustrated in <figref idref="DRAWINGS">FIGS. 3-8</figref> are depicted. In some embodiments, the major diameter (defined by the maximum radial extent of the crest portion of the thread) tapers over at least the last two revolutions of the threaded portion adjacent the second end of the fastener. To facilitate engagement of a threaded fastener, such as engagement of a screw or bolt into a threaded hole, the second end of the threaded fastener may be tapered.

0047Referring to <figref idref="DRAWINGS">FIG. 9</figref>, the threaded fastener <b>100</b> has thread <b>200</b>. Adjacent the second end <b>104</b>, the crest portion <b>202</b>, <b>202</b>′ tapers at a taper angle θ of approximately 30° as shown. Referring to <figref idref="DRAWINGS">FIG. 10</figref>, the threaded fastener <b>100</b> has thread <b>300</b>. Adjacent the second end <b>104</b>, the crest portion <b>302</b>, <b>302</b>′ tapers at a taper angle θ of approximately 30° as shown. Referring to <figref idref="DRAWINGS">FIG. 11</figref>, the threaded fastener <b>100</b> has thread <b>400</b>. Adjacent the second end <b>104</b>, the crest portion <b>402</b>, <b>402</b>′ tapers at a taper angle θ of approximately 30° as shown. In all embodiments, the taper may extend for at least the last two revolutions of the thread. In some embodiments, the taper angle θ is between 15° and 30°, and the taper may extend for three or more revolutions of the thread as may be desired. The taper angle θ may also be in the range of 0° to 60°, or 5° to 55°, or 10° to 50°, or 15° to 45°, or 20° to 40°, or 25° to 35°, or approximately 30°. In yet other embodiments, the maximum diameter of the crest portion of the thread is defined by a radius (R) greater than the major diameter of the fastener and defines a first taper angle of between 15° and 30° from the second end to the first crest portion <b>202</b>′, <b>302</b>′, <b>402</b>′ adjacent the second end, and defines a second taper angle from the first crest portion <b>202</b>′, <b>302</b>′, <b>402</b>′ to the second crest portion <b>202</b>, <b>302</b>, <b>402</b> from the second end which is less than the first taper angle θ.

0048In yet other embodiments, the first end of the threaded fastener includes a radially extending surface <b>112</b>. In an embodiment, the radially extending surface <b>112</b> is the underside of a head of the fastener, such as illustrated in <figref idref="DRAWINGS">FIG. 2</figref>. In other embodiments, the threaded fastener is a nut (or similar internally threaded structure) and the radially extending surface is the top surface of the fastener configured to mate with a component. In each embodiment, the radially extending surface may include a plurality of serrations configured to further improve the vibration resistance of the presently disclosed threaded fastener.

0049The presently disclosed threaded fastener may be made from low carbon steel, alloy steel, aluminum, brass or other materials as desired. The threaded fasteners may be made of a material for assembling parts made from plastic, brass, aluminum, wood, concrete, steel, or other component materials.

0050Experimental samples of the presently disclosed fasteners were produced and tested compared with a selection of commercially available comparative fasteners. The test results are illustrated in <figref idref="DRAWINGS">FIGS. 12-14</figref> and discussed below. Samples A-C are embodiments of the presently disclosed threaded fastener. Sample A is a fastener having a thread form configured as shown in <figref idref="DRAWINGS">FIGS. 3-4</figref>. Sample B is a fastener having thread form configured as shown in <figref idref="DRAWINGS">FIGS. 5-6</figref>. Sample C is a fastener having a thread form as shown in <figref idref="DRAWINGS">FIGS. 7-8</figref>.

0051The selection of commercially available comparative fasteners are designated as Samples D-H. Sample D is a commercially available, machine screw with serrations on the underside of the head portion and a vibration resistant nut sold under the trademark DTFLock. Sample E is a commercially available machine screw with a commercially available anti-vibration patch, serrations on the underside of the head portion, and a standard nut. Sample F is a commercially available machine screw mated with a nut having class <b>10</b> serrations. Sample G is another commercially available machine screw mated with a nut having serrations. Sample H is a commercially available machine screw mated with a nut without serrations.

0052The selected fasteners were tested for vibration loosening in a vibration test conducted at 0.25 mm amplitude and 10 Hz frequency for 2500 cycles. As shown in <figref idref="DRAWINGS">FIG. 12</figref>, the presently disclosed fastener performed better than each of the commercial available comparative fasteners. <figref idref="DRAWINGS">FIG. 12</figref> shows a plot of the vibration test results as the number of cycles increased from zero to 2500. Each fastener was installed with preload of 3.0 KN. The fasteners were then subjected to the vibration test at the amplitude and frequency mentioned above and the results monitored. As illustrated in the graph, as the number of cycles increased, all of the sample fasteners loosened due to the vibration. The presently disclosed fasteners, however, outperformed all of the commercially available fasteners, including the anti-vibration fastener Sample D. Table 1 below provides the vibration test performance results for the samples as tested.

0053<tables id="TABLE-US-00001" num="00001"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="217pt" align="center" /><thead><row><entry namest="1" nameend="1" rowsep="1">TABLE 1</entry></row></thead><tbody valign="top"><row><entry namest="1" nameend="1" align="center" rowsep="1" /></row><row><entry>Vibration Test Results</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="1" colwidth="77pt" align="left" /><colspec colname="2" colwidth="28pt" align="center" /><colspec colname="3" colwidth="35pt" align="center" /><colspec colname="4" colwidth="35pt" align="center" /><colspec colname="5" colwidth="42pt" align="center" /><tbody valign="top"><row><entry /><entry /><entry /><entry>Remaining</entry><entry /></row><row><entry /><entry>Preload</entry><entry># Cycles </entry><entry>Preload</entry><entry>Remaining</entry></row><row><entry /><entry>(KN)</entry><entry>@ 10 Hz</entry><entry>(KN)</entry><entry>Preload (%)</entry></row><row><entry namest="1" nameend="5" align="center" rowsep="1" /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="1" colwidth="77pt" align="left" /><colspec colname="2" colwidth="28pt" align="center" /><colspec colname="3" colwidth="35pt" align="center" /><colspec colname="4" colwidth="35pt" align="center" /><colspec colname="5" colwidth="42pt" align="char" char="." /><tbody valign="top"><row><entry>Sample C (FIGS. 7-8)</entry><entry>3.0</entry><entry>2500</entry><entry>2.84</entry><entry>94.67</entry></row><row><entry>Sample B (FIGS. 5-6)</entry><entry>3.0</entry><entry>2500</entry><entry>2.83</entry><entry>94.33</entry></row><row><entry>Sample A (FIGS. 3-4)</entry><entry>3.0</entry><entry>2500</entry><entry>2.80</entry><entry>93.33</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="217pt" align="center" /><tbody valign="top"><row><entry>Comparative Fasteners</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="1" colwidth="77pt" align="left" /><colspec colname="2" colwidth="28pt" align="center" /><colspec colname="3" colwidth="35pt" align="center" /><colspec colname="4" colwidth="35pt" align="center" /><colspec colname="5" colwidth="42pt" align="char" char="." /><tbody valign="top"><row><entry>Sample D</entry><entry>3.0</entry><entry>2500</entry><entry>2.57</entry><entry>85.67</entry></row><row><entry>Sample E</entry><entry>3.0</entry><entry>2500</entry><entry>1.21</entry><entry>40.33</entry></row><row><entry>Sample F</entry><entry>3.0</entry><entry>2500</entry><entry>0.74</entry><entry>24.67</entry></row><row><entry>Sample G</entry><entry>3.0</entry><entry>2500</entry><entry>0.73</entry><entry>24.33</entry></row><row><entry>Sample G</entry><entry>3.0</entry><entry>2500</entry><entry>0.01</entry><entry>0.33</entry></row><row><entry namest="1" nameend="5" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0054As shown above, Sample B achieved the best performance in the test with greater than a 10% improvement in vibration resistance as compared to Sample D.

0055In addition to improved vibration resistance, the presently disclosed fasteners also provide superior pull-out strength, more uniform distribution of stresses, lower drive torque, and better drive torque to failure torque performance, among other benefits.

0056<figref idref="DRAWINGS">FIG. 13</figref> is a chart of seating torque. Samples of the disclosed threaded fastener were prepared at both the mean dimensions and maximum dimensions for the selected fastener size. For comparison, a standard machine screw was tested with and without a nylon patch. As shown, each sample of the presently disclosed fastener performed better than machine screws.

0057<figref idref="DRAWINGS">FIG. 14</figref> is a chart of torque off test results. Samples of the presently disclosed threaded fastener were prepared at both the mean dimensions and maximum dimensions for the selected fastener size. For comparison, a standard machine screw was tested with and with a nylon patch. As shown, each sample of the presently disclosed fastener performed better than machine screws.

0058In the specification and claims, reference will be made to a number of terms that have the following meanings. The singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term such as “about” or “approximately” is not to be limited to the precise value specified. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Moreover, unless specifically stated otherwise, any use of the terms “first,” “second,” etc., do not denote any order or importance, but rather the terms “first,” “second,” etc., are used to distinguish one element from another.

0059As used herein, the terms “may” and “may be” indicate a possibility of an occurrence within a set of circumstances; a possession of a specified property, characteristic or function; and/or qualify another verb by expressing one or more of an ability, capability, or possibility associated with the qualified verb. Accordingly, usage of “may” and “may be” indicates that a modified term is apparently appropriate, capable, or suitable for an indicated capacity, function, or usage, while taking into account that in some circumstances the modified term may sometimes not be appropriate, capable, or suitable. For example, in some circumstances an event or capacity can be expected, while in other circumstances the event or capacity cannot occur—this distinction is captured by the terms “may” and “may be.”

0060This invention has been described with reference to illustrative embodiments and is not meant to be construed in a limiting sense. It will be apparent to one skilled in the art that elements or process steps from one or more embodiments described herein may be used in combination with elements or process steps from one or more other embodiments described herein, and that the present invention is not limited to the specific embodiments provided herein but only as set forth in the accompanying claims. Various modifications of the illustrative embodiments, as well as additional embodiments to the invention will be apparent to persons skilled in the art upon reference to this description.